Conjugation energy and relative stability of borazole and some heterocyclic molecules containing boron and nitrogen atoms

1963 ◽  
Vol 12 (5) ◽  
pp. 711-714
Author(s):  
D. A. Bochvar ◽  
A. A. Bagatur'yants
Keyword(s):  
Relative Stability ◽  
Heterocyclic Molecules ◽  
Conjugation Energy

Synthesis of Drugs and Biorelevant N-heterocycles Employing Recent Advances in C-N Bond Formation

2020 ◽  
Vol 24 (20) ◽  
pp. 2293-2340
Author(s):  
Firdoos Ahmad Sofi ◽  
Prasad V. Bharatam
Keyword(s):  
Kinase Inhibitors ◽  
Bond Formation ◽  
Comprehensive Review ◽  
Biologically Relevant ◽  
Lead Compounds ◽  
Heterocyclic Molecules ◽  
The Past ◽  
Anti Cancer ◽  
Modern Methods ◽  
Bond Formation Reactions

C-N bond formation is a particularly important step in the generation of many biologically relevant heterocyclic molecules. Several methods have been reported for this purpose over the past few decades. Well-known named reactions like Ullmann-Goldberg coupling, Buchwald-Hartwig coupling and Chan-Lam coupling are associated with the C-N bond formation reactions. Several reviews covering this topic have already been published. However, no comprehensive review covering the synthesis of drugs/ lead compounds using the C-N bond formation reactions was reported. In this review, we cover many modern methods of the C-N bond formation reactions, with special emphasis on metal-free and green chemistry methods. We also report specific strategies adopted for the synthesis of drugs, which involve the C-N bond formation reactions. Examples include anti-cancer, antidepressant, anti-inflammatory, anti-atherosclerotic, anti-histaminic, antibiotics, antibacterial, anti-rheumatic, antiepileptic and anti-diabetic agents. Many recently developed lead compounds generated using the C-N bond formation reactions are also covered in this review. Examples include MAP kinase inhibitors, TRKs inhibitors, Polo-like Kinase inhibitors and MPS1 inhibitors.

Synthesis, Antiproliferative Activity and Molecular Docking of New Thiazole/Benzothiazole Fused Pyranopyrimidine Derivatives

2020 ◽  
Vol 17 (12) ◽  
pp. 951-958
Author(s):  
Pallava Nagaraju ◽  
Pedavenkatagari Narayana Reddy ◽  
Pannala Padmaja ◽  
Vinod G. Ugale
Keyword(s):  
Molecular Docking ◽  
Cell Lines ◽  
Antiproliferative Activity ◽  
Aromatic Aldehydes ◽  
Human Colon ◽  
Docking Studies ◽  
Human Colon Cancer ◽  
One Pot ◽  
Human Embryonic Kidney Cells ◽  
Heterocyclic Molecules

A new class of 4H,5H-benzo[4,5]thiazolo[3,2-a]pyrano[2,3-d]pyrimidin-5-one and 5H,6Hpyrano[ 2,3-d]thiazolo[3,2-a]pyrimidin-5-one derivatives were synthesized via the one-pot threecomponent reaction of 2-hydroxy-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-one and 7-hydroxy-5Hthiazolo[ 3,2-a]pyrimidin-5-one to various aromatic aldehydes and malononitrile. This domino transformation involves the formation of pyranopyrimidine ring by the formation of three C–C bonds and one C– O bond a single synthetic operation. As the products precipitate out of the reaction, simple filtration is enough to gather the products, and thus, there is no need for work-up or column-chromatography. The synthesized thiazole/benzothiazole fused pyranopyrimidine derivatives were evaluated for their antiproliferative activity against four cancer cell lines namely DU 145 (prostate cancer), Hela (Human cervical cancer), MDA-MB-231 (breast cancer), HT-29 (Human colon cancer) and normal cell line HEK293 (human embryonic kidney cells). The results demonstrated that synthesized compounds were selective in its cytotoxicity to cancer cells compared to normal cells. Among these compounds, 2-amino-9- methoxy-5-oxo-4-(3,4,5-trimethoxyphenyl)-4H,5H-benzo[4,5]thiazolo[3,2-a]pyrano[2,3-d]pyrimidine- 3-carbonitrile 4i exhibited the most potent antiproliferative activity against the tested cell lines. Molecular docking studies revealed that these active heterocyclic molecules bind selectively in the colchicine binding site of tubulin polymer.

Metal and Non-Metal Catalysts in the Synthesis of Five-Membered S-Heterocycles

2019 ◽  
Vol 16 (2) ◽  
pp. 258-275 ◽  
Author(s):  
Navjeet Kaur
Keyword(s):  
Organic Synthesis ◽  
Biological Activities ◽  
Reaction Times ◽  
Research Field ◽  
Environmentally Benign ◽  
Metal Catalyst ◽  
Efficient Synthesis ◽  
Heterocyclic Molecules ◽  
The Past ◽  
Harsh Conditions

Background:A wide variety of biological activities are exhibited by N, O and S containing heterocycles and recently, many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal and non-metal catalyst has become a highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of S-heterocylces in the presence of metal and non-metal catalyst. The synthesis of five-membered S-heterocycles is described here.Objective:There is a need for the development of rapid, efficient and versatile strategy for the synthesis of heterocyclic rings. Metal, non-metal and organocatalysis involving methods have gained prominence because traditional conditions have disadvantages such as long reaction times, harsh conditions and limited substrate scope.Conclusion:The metal-, non-metal-, and organocatalyst assisted organic synthesis is a highly dynamic research field. For ßthe chemoselective and efficient synthesis of heterocyclic molecules, this protocol has emerged as a powerful route. Various methodologies in the past few years have been pointed out to pursue more sustainable, efficient and environmentally benign procedures and products. Among these processes, the development of new protocols (catalysis), which avoided the use of toxic reagents, are the focus of intense research.

The Molecular Diversity Scope of Urazole in the Synthesis of Organic Compounds

2019 ◽  
Vol 16 (7) ◽  
pp. 953-967 ◽  
Author(s):  
Ghodsi M. Ziarani ◽  
Fatemeh Mohajer ◽  
Razieh Moradi ◽  
Parisa Mofatehnia
Keyword(s):  
Biological Activities ◽  
Biological Properties ◽  
Biologically Active ◽  
Microtubule Assembly ◽  
Heterocyclic Molecules ◽  
Biological Perspective ◽  
Highly Active ◽  
Anti Inflammatory ◽  
High Yields ◽  
Short Time

Background: As a matter of fact, nitrogen as a hetero atom among other atoms has had an important role in active biological compounds. Since heterocyclic molecules with nitrogen are highly demanded due to biological properties, 4-phenylurazole as a compound containing nitrogen might be important in the multicomponent reaction used in agrochemicals, and pharmaceuticals. Considering the case of fused derivatives “pyrazolourazoles” which are highly applicable because of their application for analgesic, antibacterial, anti-inflammatory and antidiabetic activities as HSP-72 induction inhibitors (I and III) and novel microtubule assembly inhibitors. It should be mentioned that spiro-pyrazole also has biological activities like cytotoxic, antimicrobial, anticonvulsant, antifungal, anticancer, anti-inflammatory, and cardiotonic activities. Objective: Urazole has been used in many heterocyclic compounds which are valuable in organic syntheses. This review disclosed the advances in the use of urazole as the starting material in the synthesis of various biologically active molecules from 2006 to 2019. Conclusion: Compounds of urazole (1,2,4-triazolidine-3,5-dione) are the most important molecules which are highly active from the biological perspective in the pharmaceuticals as well as polymers. In summary, many protocols for preparations of the urazole derivatives from various substrates in multi-component reactions have been reported from different aromatic and aliphatic groups which have had carbonyl groups in their structures. It is noted that several catalysts have been synthesized to afford applicable molecules with urazole scaffolds. In some papers, being environmentally friendly, short time reactions and high yields are highlighted in the protocols. There is a room to synthesize new catalysts and perform new reactions by manipulating urazole to produce biologically active compounds, even producing chiral urazole component as many groups of chiral urazole compounds are important from biological perspective.

Aromaticity in heterocyclic molecules containing divalent sulfur

1988 ◽  
Vol 53 (9) ◽  
pp. 2023-2054 ◽  
Author(s):  
Milan Randić ◽  
Sonja Nikolić ◽  
Nenad Trinajstić
Keyword(s):  
Sulfur Atom ◽  
Positional Isomers ◽  
Heterocyclic Molecules ◽  
Resonance Energies ◽  
Conjugated Circuits ◽  
Divalent Sulfur

The conjugated circuits model is applied to heterocycles containing divalent sulfur. A novel parametrization is introduced for 4n + 2 and 4n conjugated circuits containing a single sulfur atom. The relative aromatic stabilities of a number of heterocyclic systems containing divalent sulfur are studied. Comparison is made whenever possible with earlier reported resonance energies of these compounds, obtained by using Huckel MO and SCF π-MO models, and appropriate reference structures. Special attention is given to positional isomers. An explanation of the differences amongst such isomers is given.

Equilibrium Studies of Binary and Ternary Complexes of Palladium(II) Involving Amino Acids

1993 ◽  
Vol 58 (5) ◽  
pp. 1103-1108 ◽  
Author(s):  
Mohamed M. Shoukry ◽  
Eman M. Shoukry
Keyword(s):  
Amino Acids ◽  
Relative Stability ◽  
Ternary Complex ◽  
Formation Constants ◽  
Ternary Complexes ◽  
Conductivity Measurements ◽  
Equilibrium Studies ◽  
Binary And Ternary Complexes ◽  
Binary Complexes

The formation constants of the binary and ternary complexes of palladium(II) with diethylenetriamine and amino acids as ligands have been determined potentiometrically at 25 °C in 0.1 M NaNO3 solution. The relative stability of each ternary complex was compared with that of the corresponding binary complexes in terms of ∆logK values. The mode of chelation was ascertained by conductivity measurements.

scholarly journals A Novel Index (RI) to Evaluate the Relative Stability of Soils Using Ultrasonic Agitation

2021 ◽  
Vol 13 (8) ◽  
pp. 4229
Author(s):  
Fakher Abbas ◽  
Fang Lin ◽  
Zhaolong Zhu ◽  
Shaoshan An
Keyword(s):  
Relative Stability ◽  
Characteristic Curve ◽  
Geometric Mean ◽  
Relative Strength ◽  
Soil Stability ◽  
Dispersion Energy ◽  
Ultrasonic Agitation ◽  
Mean Weight Diameter ◽  
Change In Mean ◽  
Wet Sieving

As soil stability is a complex phenomenon, various methods and indexes were introduced to assess the strength of soils. Because of the limitations of different stability methods and indexes (including wet sieving-based), we aimed to presents a relative stability index (RI) that was based on the estimated components of the soil overall disruptive characteristic curve (SODC): (1) soil disruption constant (Ki, that is based upon dispersion energy of soils); (2) resulting change in mean weight diameter (ΔMWD). To evaluate the effectiveness and limitations of RI as well as to compare it with classical soil stability indexes of mean weight diameter (MWD) and geometric mean diameter (GMD). Ultrasonic agitation (UA) along with a wet sieving method (followed by dry sieving) was applied against four different soils named on the basis of sample location, Qingling soil (QL), Guanzhong soil (GZ), Ansai soil (AS), and Jingbian soil (JB). To evaluate the relative strength of soils at different applied energies (increase in sonication duration usually resulted in increased input energy and temperature of soil–water suspension), soils were subjected to six sonication durations (0, 30, 60, 120, 210, and 300 s) with a fixed (and exact) initial amplitude and temperature. Output energy was calculated based on the amplitude and temperature of the suspension, vessel, and system. The most abrupt and maximum disruption of soil aggregates was observed at a dispersion energy level of 0–200 J g−1. The MWD value of surface and subsurface ranged between 0.58 to 0.15 mm and 0.37 to 0.17 mm, respectively, while GMD was ranged from 0.14 to 0.33 mm overall. The results for MWD and GMD showed a similar trend. MWD and GMD showed more strong associations with physicochemical characteristics of soil than RI. A non-significant correlation was found between RI and MWD/GMD. Contrary to MWD and GMD, RI was significantly positively correlated with sand content; this finding indicated the influential role of sand in assessing the soil’s relative strength. The results indicated that JB soil possessed the least MWD and GMD but proved to be relatively stable because of having the highest RI value.

A Convenient Protecting Group for Uridine Ureido Nitrogen: (4,4′-Bisfluorophenyl)methoxymethyl Group

Synthesis ◽  
2021 ◽  
Author(s):  
Michio Kurosu ◽  
Katsuhiko Mitachi ◽  
David Mingle
Keyword(s):  
Chemical Transformation ◽  
Relative Stability ◽  
Protecting Group

Abstract(4,4′-Bisfluorophenyl)methoxymethyl (BFPM) group of uridine ureido nitrogen shows good relative stability in a variety of chemical transformation reactions for uridine. The BFPM group can be cleaved by 2% of TFA in CH2Cl2 without affecting the Boc group.

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